Minimally invasive surgical access device

ABSTRACT

A minimally invasive surgical access device that allows access to a pathology being treated while significantly reducing the risk of damaging anatomical structures proximate the pathology. The access device includes a base portion having a central bore extending therethrough, and retractor blades pivotably mounted to the base portion. An insertion handle is coupled to the base portion to thread the retractor blades into the patient. The insertion handle is removed from the base portion, and a core hollow screw is threaded into the base portion to separate the retractor blades to gain access to the pathology through the hollow screw.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a minimally invasive access devicefor a surgical procedure and, more particularly, to a minimally invasiveaccess device for spinal surgery, where the device includes retractorblades and an access tube, where the access tube is threaded into theretractor blades to cause them to separate, which provides a corridorfor accessing a surgical pathology.

2. Discussion of the Related Art

Traditional surgical approaches for the human body involve thedissection of supporting structures, such as muscle, ligaments and/orbone, to access and expose the pathology being treated. These structuresare usually vital to the long term health and function of the body.Typically, these structures are not involved in a disease process, butfrequently need to be removed or dissected in order to gainvisualization of the pathology.

In the case of spinal disorders, the supporting muscle and ligaments ofthe spine are removed to expose the underlying bony part of the spinewhere the pathology is typically located. These supporting structuresare not causing the patient any discomfort or pain, however, because thesurgeon must be able to visualize the surgical operation, they need tobe removed or detached. For example, in the treatment of a lumbar diskherniation or stenosis, the muscle and ligaments are dissected from thespine to expose the lamina of the spine, sometimes over many levels ofthe spine. In performing spinal fusion and instrumentation, extensivemuscle and ligamentous detachment may be performed. As a result, thesetissues never return to their normal anatomical position, which isdisrupted in the surgical process, weakening their function andstrength. Also, the patient may experience significant pain anddiscomfort resulting in longer hospital stays and recoveries. The longterm health of the spine can also be affected because these supportingstructures are not able to perform their function normally. This canresult in further pain and discomfort, and can even lead to additionalsurgeries.

A frequently encountered problem is transitional syndrome whereby thenerves adjacent to an open fusion and instrumentation become compressed.The treatment is often an additional surgery with extension of thefusion and instrumentation. This may in-part be due to the initialfusion procedure dissecting supporting muscles and ligaments creating aniatrogenic instability that leads to adjacent level stenosis. Inaddition, large open procedures often result in extensive scar formationthat can lead to conditions such as arachnoiditis and failed backsyndrome. These patients suffer significant and debilitating pain whichis often refractory to additional surgery. Many can no longer work orconduct normal activities of daily living.

In an attempt to preserve normal anatomical structures during spinesurgery, minimally invasive surgical procedures have been devised. Onesuch procedure involves the use of a series of muscle dilators thatspread open the muscle fibers of the spine to create a pathway to thespine. A Kirschner (K) wire (a thin metal wire) is initially introducedthrough a small incision and directed towards the spinal pathology. Theposition of the K-wire is visualized by a fluoroscopic imaging system toidentify its location. An initial narrow diameter muscle dilator ispassed over the K-wire, and the K-wire is removed and subsequent largermuscle dilators are continually passed. When the opening is largeenough, an access tube or retractor is positioned around the last muscledilator through which the surgery is performed. The inner sequentialmuscle dilators are then removed allowing the surgeon to operate throughthe tubular retractor. The retractors come in a variety of lengths anddiameters for different patients and procedures.

Unfortunately, a number of complications have occurred using thepreviously described system. The K-wire is very thin and sharp and canbe easily passed to deep and into the spinal cord or injure a nerve rootor large blood vessel. Additionally considerable downward force isrequired to pass the muscle dilators towards the spine. Incidences haveoccurred in which the dilators are passed into the spinal canalresulting in neural injury and paralysis. The muscle dilators also tendto be pushed upward out of the wound requiring multiple repositioningduring placement, each time placing the neural structures at risk. Thisis especially true for large muscular individuals. Lastly, multiple,sequentially larger dilators are used causing considerable patient riskwith placement of each muscle dilator. Therefore, it is desirable toimprove the known minimally invasive surgical access devices.

SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, a minimallyinvasive surgical access device is disclosed that allows access to apathology being treated while significantly reducing the risk ofdamaging anatomical structures proximate the pathology. The accessdevice includes a base portion having a bore extending therethrough.Retractor blades including inner and outer threads are pivotably mountedto the base portion. An insertion handle having an elongated body isattached to and extends through the bore in the base portion, andincludes tabs for holding the retractor blades together in a conicalorientation. The insertion handle is used to thread the retractor bladesinto the soft tissue of the patient towards the pathology. When theretractor blades are in place, the insertion handle is removed from thebase portion, and a core hollow screw having a threaded outer portion isinserted through the opening of the base portion. An access handle isattached to the core hollow screw and is used to rotate the core hollowscrew so that the threaded portion of the core hollow screw and theinternal threads of the retractor blades interact to separate theretractor blades and expose the pathology through an internal bore inthe core hollow screw.

Additional features of the present invention will become apparent fromthe following description and appended claims, taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a base portion including pivotableretractor blades of a surgical access device assembly, according to anembodiment of the present invention;

FIG. 2 is a top view of the base portion shown in FIG. 1;

FIG. 3 is a perspective view of an insertion handle that attaches to thebase portion of the access device assembly to thread the retractorblades through soft tissue of a patient;

FIG. 4 is a perspective view of the insertion handle mounted to the baseportion of the access device assembly;

FIG. 5 is an enlarged view of a portion of the retractor blades of thebase portion showing how the retractor blades are locked together whenthe insertion handle is mounted to the base portion;

FIG. 6 is a front view of a core hollow screw that is threadablyengagable with the retractor blades of the base portion;

FIG. 7 is a front view of an access handle that attaches to the corehollow screw to threadably insert the core hollow screw into the baseportion;

FIG. 8 is a front view of the access handle attached to the core hollowscrew;

FIG. 9 is a perspective view of the core hollow screw threaded into theretractor blades to expose the pathology being treated; and

FIG. 10 is a top view of the base portion with the core hollow screwinserted into the retractor blades.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion of the embodiments of the invention directed toa minimally invasive surgical access device is merely exemplary innature, and is in no way intended to limit the invention or itsapplications or uses. For example, the access device of the inventionhas particular application for minimally invasive spinal surgicalprocedures. However, as will be appreciated by those skilled in the art,the access device of the invention will have application for other typesof minimally invasive surgeries.

FIGS. 1-10 show various views of various components of a minimallyinvasive surgical access device assembly 10, according to an embodimentof the present invention. The various components of the assembly 10 canbe fabricated and assembled by any suitable technique, such as molding,stamping, welding, etc., and can be made of any suitable material, suchas aluminum, steel, radio-lucent carbon/graphite composites, etc.

As shown in FIGS. 1 and 2, the access device assembly 10 includes around base portion 12 having a central bore 14 extending therethrough.Three small holes 16 are symmetrically disposed around the central bore14 and also extend through the base portion 12. A mounting ring 18 ispositioned around an outer edge of the base portion 12, and is clampedthereto by a bolt 20. The mounting ring 18 includes an extended portion28, where the bolt 20 is threaded through a tab 36 across a gap into theextended portion 28 to rigidly mount the mounting ring 18 to the baseportion 12. The extended portion 28 includes a threaded opening 38 thataccepts a securing bolt of a holding arm (not shown). As would be wellunderstood to those skilled in the art and more apparent from thediscussion below, when the access device assembly 10 is being used in asurgical procedure, it needs to be rigidly mounted to a supportingstructure, such as the operating table.

Three symmetrical retractor blades 22, 24 and 26 are pivotably mountedto the base portion 12. The retractor blade 22 includes an upper tab 30,the retractor blade 24 includes an upper tab 32 and the retractor blade26 includes an upper tab 34. The tabs 30, 32 and 34 each have a boreextending therethrough. The base portion 12 includes a rod (not shown)extending across an opening in the base portion 12 in which each of thetabs 30, 32 and 34 is positioned. Thus, the retractor blades 22-26 arefree to pivot on their independent rods. The retractor blades 22-26 havean inner thread and an outer thread for reasons that will becomeapparent from the discussion below. The internal and external threads ofthe retractor blades 22-26 need not be continuous between the blades22-26, but can be in other embodiments. Further, when the retractorblades 22-26 are in their unpivoted position, the retractor blades 22-26form a conical shape having a pointed end opposite to the base portion12.

As will be appreciated by those skilled in the art, a conical shape forthe retractor blades 22-26 is non-limiting in that the retractor blades22-26 can form other shapes, such as a parabolic swept section, concaveand convex orientations, stepped linear sections, a spiral, etc.Further, the cone can be unitary or broken up into multiple componentsalong its axis. Further, the cone shape can be a canculated cone toallow it to follow a K-wire to the pathology. In this embodiment, thereare three retractor blades. However, it other embodiments there may bemore retractor blades within the scope of the present invention.

As shown in FIG. 3, the access device assembly 10 also includes aninsertion handle 40 having a support portion 42 and a conical bottomportion 44. In one embodiment, the insertion handle 40 can be a singlepiece unit made from a suitable material, such as aluminum. Threecylindrical pins 46 extend down from the support portion 42 and areconfigured to be inserted into the holes 16 in the base portion 12.Further, the conical portion 44 is dimensioned to fit within theretractor blades 22-26 when the retractor blades 22-26 are in theirunpivoted position.

FIG. 4 is a perspective view of the insertion handle 40 attached to thebase portion 12. The conical portion 44 includes three extending tabs 48that are configured to be positioned within openings 50 between theretractor blades 22-26 at an upper location proximate the base portion12. FIG. 5 is a blown-up view at this location of the assembly 10. Thetabs 48 include a pair of fingers 52 that are inserted within notches 54in two adjacent retractor blades 22-26 so that when the insertion handle40 is positioned in the base portion 12, the retractor blades 22-26 areheld in place and prevented from pivoting.

When the access handle 40 is positioned in the base portion 12, thepointed end of the retractor blades 22-26 are positioned over thepathology on the patient's skin. The handle 40 is rotated to thread theretractor blades 22-26 into the patient towards the pathology. The pins46 in the support portion 42 prevent the handle 40 from being rotatedrelative to the base portion 12. Once the retractor blades 22-26 arefully inserted into the patient to the desired depth, the handle 40 canbe removed from the base portion 12 by merely pulling up on it. Theretractor blades 22-26 are unique in allowing for a single pass oraccess towards the spine, and once positioned and opened, to expose thespinal pathology while minimizing muscle or ligamentous resection. Thescrew type outer conical design allows for a controlled approach sincethe driving force to advance the retractor blades 22-26 toward the spineis a turning motion, not a downward forced motion. The rate ofadvancement of the tip of the retractor blades 22-26 is controlled atall times by the rate of rotation of the insertion handle 40. Thissignificantly improves the safety of the assembly 10 for accessing thepathology.

FIG. 6 is a front view of a core hollow screw 60 that is part of theassembly 10. The core hollow screw 60 includes an outer threaded portion62 at a bottom of the core hollow screw 60 that aligns with the innerthreads of the retractor blades 22-26. A top edge of the core hollowscrew 60 includes four symmetrically disposed cut-outs 64.

FIG. 7 is a front view of an access handle 70 including an elongated rod72 and an end portion 74 having symmetrically disposed pins 76. FIG. 8is a front view of the access handle 70 mounted to the core hollow screw60 where the end portion 74 is positioned within an internal bore 80 ofthe core hollow screw 60 and the pins 76 are positioned within thecut-outs 64.

When the insertion handle 40 is removed from the base portion 12 afterthe retractor blades 22-26 are threaded into the patient, the surgeonwill attach the access handle to the core hollow screw 60 and thenposition the threaded portion 62 of the core hollow screw 60 into thecentral bore 14 of the base portion 12. When the surgeon rotates theaccess handle 70 to turn the core hollow screw 60, the threaded portion62 of the core hollow screw 60 and the retractor blades 22-26 interactto cause the core hollow screw 60 to be threaded downward, which causesthe retractor blades 22-26 to pivot and separate.

FIG. 9 is a perspective view of the access device assembly 10, where thescrew tube 60 has been threaded into the retractor blades 22-26. Thedistance that the core hollow screw 60 is inserted into the retractorblades 22-26 would depend on the surgical procedure being performed andthe pathology being treated. Once the core hollow screw 60 is threadedinto the retractor blades 22-26 to the proper distance, the handle 70 isremoved from the core hollow screw 60, by pulling up on it. The internalbore 80 of the core hollow screw 60 is used to gain access to thepathology to perform the surgical procedure. FIG. 10 is a top view ofthe base portion 12 with the core hollow screw 60 in place showing theinternal bore 80 through which the surgical procedure is performed.Different size access device assemblies including different diameter andlength core hollow screws can be provided for treating differentpathologies.

The discussion of the access device assembly 10 above has particularapplication for minimally invasive spinal surgery where the retractorblades are threaded through the patient's tissue towards the pathology.In alternate embodiments, the retractor blades 22-26 can beself-drilling through facia, muscle and soft tissue. Further, theretractor blades 22-26 may be able to be drilled into bone or cartilageto provide for nail entry portals, cranial access ports, bone compactionto prepare an ACL tunnel, tendon repair tunnel preparation, sutureanchor, etc. The bone cutting version could have a cutting flute insteadof the external threads on the retractor blades 22-26.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion and from the accompanyingdrawings and claims that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention as defined in the following claims.

1. A surgical access device assembly comprising: a base portionincluding a central bore; a plurality of retractor blades pivotablymounted to the base portion and including an internal threaded portion,said plurality of retractor blades combining to form a predeterminedinternal shape in a closed position having a pointed end opposite to thebase portion, said plurality of retractor blades including an externalthreaded portion operable to be threaded into a patient; and a firsthandle having an elongated body and an end portion that conforms to thepredetermined internal shape of the plurality of retractor blades whenthe retractor blades are in the closed position, said retractor bladesincluding a locking structure for securing the retractor blades in theclosed position, said handle being rotatable so that the retractorblades are rotatable.
 2. The assembly according to claim 1 wherein thebase portion includes a plurality of holes and the first handle includesa plurality of pins positionable within the holes to hold the firsthandle to the base portion as it is rotated.
 3. The assembly accordingto claim 1 wherein each of the plurality of retractor blades includes anupper tab that is pivotably mounted to a rod positioned within anopening in the base portion.
 4. The assembly according to claim 1wherein the end portion of the first handle includes a plurality ofsymmetrically disposed tabs having extended fingers and each of theplurality of retractor blades includes a notch portion where the fingersof the tabs are positioned within the notch portion to form the lockingstructure.
 5. The assembly according to claim 1 wherein the plurality ofretractor blades is three or more retractor blades.
 6. The assemblyaccording to claim 1 wherein the predetermined internal shape isselected from the group consisting of conical shapes, a parabolic sweptsection, concave shapes, convex shapes, stepped linear sections andspirals.
 7. The assembly according to claim 1 further comprising a corehollow screw having an external threaded portion, said core hollow screwbeing operable to be threaded into the predetermined internal shapeformed by the plurality of retractor blades when the first handle isremoved from the base portion to cause the plurality of retractor bladesto separate.
 8. The assembly according to claim 7 further comprising asecond handle having an elongated body, said second handle beingattachable and detachable to and from the core hollow screw to threadthe core hollow screw into the plurality of retractor blades.
 9. Theassembly according to claim 8 wherein the second handle includes aplurality of symmetrically disposed pins and the core hollow screwincludes a plurality of symmetrically disposed cut-outs at a top edge ofthe core hollow screw where the pins on the second handle are positionedwithin the cut-outs to secure the second handle to the core hollowscrew.
 10. The assembly according to claim 1 further comprising amounting ring rigidly mounted to an outer surface of the base portion,said mounting ring including an extended portion that is adaptable toreceive a mounting arm.
 11. A surgical access device assemblycomprising: a base portion including a central bore; a plurality ofretractor blades pivotably mounted to the base portion and including aninternal threaded portion, said plurality of retractor blades combiningto form a predetermined internal shape in a closed position having apointed end opposite to the base portion, said plurality of retractorblades including an external threaded portion operable to be threadedinto a patient; and a core hollow screw having an internal bore and anexternal threaded portion, said core hollow screw being operable to bethreaded into the predetermined internal shape formed by the pluralityof retractor blades to cause the plurality of retractor blades toseparate.
 12. The assembly according to claim 11 wherein each of theplurality of retractor blades includes an upper tab that is pivotablymounted to a rod positioned within an opening in the base portion. 13.The assembly according to claim 11 wherein the plurality of retractorblades is three or more retractor blades.
 14. The assembly according toclaim 11 wherein the predetermined internal shape is selected from thegroup consisting of conical shapes, a parabolic swept section, concaveshapes, convex shapes, stepped linear sections and spirals.
 15. Theassembly according to claim 11 further comprising a handle having anelongated body of various length, said handle being attachable anddetachable to and from the core hollow screw to thread the core hollowscrew into the plurality of retractor blades.
 16. The assembly accordingto claim 15 wherein the handle includes a plurality of symmetricallydisposed pins and the core hollow screw includes a plurality ofsymmetrically disposed cut-outs at a top edge of the core hollow screwwhere the pins on the handle are positioned within the cut-outs tosecure the handle to the core hollow screw.
 17. The assembly accordingto claim 11 further comprising a mounting ring rigidly mounted to anouter surface of the base portion, said mounting ring including anextended portion that is adaptable to receive a mounting arm.
 18. Asurgical access device assembly comprising: a circular base portionincluding a circular central bore, said base portion further including aplurality of symmetrically disposed holes around the central bore; aplurality of retractor blades pivotably mounted to the base portion andincluding an internal threaded portion and an external threaded portion,each of the plurality of retractor blades including an upper tabpivotably mounted on a rod mounted in an opening of the base portion,said plurality of retractor blades combining to form a conical shape ina closed position having a pointed end opposite to the base portion; afirst handle including an elongated body and a conical end portion thatconforms to the internal shape of the plurality of retractor blades whenthe retractor blades are in the closed position, said first handlefurther including a plurality of symmetrically disposed pins mounted toa central support portion of the first handle that align with thesymmetrically disposed holes in the base portion so as to allow the baseportion to be rotated by the first handle when the first handle isattached to the base portion, said conical end portion of the firsthandle including a plurality of tab portions that interlock withinopenings between the plurality of retractor blades for securing theretractor blades in the closed position; a core hollow screw having aninternal bore and an external threaded portion; and a second handlehaving an elongated body and being attachable and detachable to and fromthe core hollow screw, said second handle being operable to thread thecore hollow screw into the plurality of retractor blades when the firsthandle is removed from the base portion to cause the plurality ofretractor blades to separate.
 19. The assembly according to claim 18wherein the plurality of retractor blades is three or more retractorblades.
 20. The assembly according to claim 18 wherein the second handleincludes a plurality of symmetrically disposed pins and the core hollowscrew includes a plurality of symmetrically disposed cut-outs at a topedge of the core hollow screw where the pins on the second handle arepositioned within the cut-outs to secure the second handle to the corehollow screw.
 21. The assembly according to claim 18 further comprisinga mounting ring rigidly mounted to an outer surface of the base portion,said mounting ring including an extended portion that is adaptable toreceive a mounting arm.
 22. The assembly according to claim 18 whereinthe plurality of tab portions is three symmetrically disposed tabportions including extended fingers and wherein each of the plurality ofretractor blades includes a notch portion in which the fingers of thetab portions are positioned within.